Three isotopes of argon occur in nature – 36 18Ar, 38 18Ar, 40 18Ar. Calculate the average atomic mass of argon to two decimal places, given the following relative atomic masses and the abundances of each of the isotopes: argon36 (35.97 amu; 0.337%), argon-38 (37.96 amu; 0.063%), argon-40 (39.96 amu; 99.600%).

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quasarJose quasarJose · Answer 1 · 2019-10-04T03:16:59+02:00

Answer:

39.95amu

Explanation:

Given parameters:

Relative atomic mass of Ar-36 = 35.97amu abundance = 0.337%

Relative atomic mass of Ar-38 = 37.96amu abundance = 0.063%

Relative atomic mass of Ar-40 = 39.96amu abundance = 99.600%

Unkown:

Relative atomic mass of Ar = ?

Solution:

The relative atomic mass is the average mass of all the isotopes of an element. To solve for the average atomic mass, we use the expression below:

RAM = m₃₆α₃₆ + m₃₈α₃₈ + m₄₀α₄₀

where m is the mass of the isotope

α is the abundance of the isotope

RAM of Argon = ([tex]\frac{0.337}{100}[/tex] x 35.97) + ([tex]\frac{0.063}{100}[/tex] x 37.96) +([tex]\frac{99.6}{100}[/tex] x 39.96)

RAM of Argon = 39.95amu